The pharmacology of the D-1 receptor was investigated with biochemical techniques. The binding of (125I) SCH 23982 to specific binding sites in the caudate putamen and s. nigra of the rat brain was characterized. The nonspecific binding of this ligand to melanin was also investigated. This latter signal formed the basis for the noninvasive imaging of pigmented melanomas. The role of cAMP and calcium in the process of pituitary hormone release was investigated. cAMP elevation in the 7315c tumor cell potentiates the capacity of the cell to respond to a fixed increment in the concentration of cytosolic calcium without changing the molar potency of calcium as a stimulatory agent. The substrates for cAMP-dependent protein kinase endogenous to the pituitary gland were characterized in FY 86. A number of phosphate receptors were identified.